Central Valley towns on high alert over large runoff

Central Valley towns on high alert over runoff
May 17, 2011 7:22:45 PM PDT
California could face a serious flooding threat this spring, if the snow in the Sierra begins to melt all at once. In fact, some towns in the Central Valley have already been placed on alert.

This past winter will be remembered for near record snowfall in the high Sierra. While the huge snowpack is a bounty for California's water situation, it could also create big problems for those downstream.

"The main area of concern is in the San Joaquin River Valley," said Dave Rizzardo, the chief of California's snow surveys.

"With that much snow sitting in the central and southern Sierra and those reservoirs are already full, they're going to have a major juggling act between now and June to pass that flow through the reservoirs and down into the river and into the valley without inundating the system," said Rizzardo.

Already major rivers are running high, especially in the San Joaquin Valley where the waterways are much narrower than those to the north in the Sacramento Valley. So far, state managers have released water gradually from bloated reservoirs like Melones and Don Pedro, but if the weather gets too warm, too soon, things could change in a hurry.

"If it gets really hot, undoubtedly the flows will come down in a way that will create flood issues," said Joseph Countryman from MBK Engineers.

Countryman is the former chief of flood operations for the Army Corps of Engineers.

"We have a snowpack now that's going to provide more water than we can deal with. It's going to fill all the reservoirs. We're not going to have any reservoirs that are going to have any empty space in them," said Countryman.

"The levees are carrying water right now and they're going to be carrying it for two months."

In San Joaquin County, the area of most concern is at Vernalis, west of Modesto, where fragile levees have been saturated for weeks.

"This is the chokepoint in the San Joaquin. All the water that comes out of the San Joaquin and all its tributaries, the Tuolomne, the Merced, and the Stanislaus, all comes together here and it has got to come through this channel," said Ron Baldwin from the San Joaquin County Office of Emergency Services.

In 1983, a major levee broke, flooding a vineyard, and prompting the evacuation of nearby residents.

Though there have been some improvements since then, the Central Valley system with its limited capacity and aging levees is much the same as it was and just as vulnerable. In Stanislaus County, near Newman, a trailer resort and several others have already been evacuated because of the high water.

"These are resort kind of trailer parks along the river bottom and we had to do some evacuations as the water started to encroach upon some of the living pads, we had to move them up for safety reasons," said Gary Hinshaw from the Stanislaus County Office of Emergency Services.

When asked, what happens when the water is expected to come down for a couple of months, Park Manager Bobby Atwell said, "Well, we'll be right on it, every day. We'll work at it every day to keep it out of here."

For the valley residents, this spring and summer, the bulging river will be a constant reminder that sometimes there is too much of a good thing.


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